A study on fuel spray pattern control of fuel injector of gasoline direct injection engines

摘要

We examine experimentally and numerically the influences of nozzle geometry on spray angle and penetration length. Swirl-type DI fuel injectors with an L- cut orifice nozzle (L-type) and a taper-cut orifice nozzle (Taper-type) are newly designed. The new injectors are used to spray fuel inside an experimental pressure chamber. The resulting spray patterns are visualized by YAG-laser sheet and recorded by CCD cameras. These experiments showed that both the L- type and taper-type nozzles can produce an inclined fuel-spray pattern. Furthermore, the fuel-spray pattern can be controlled by changing the depth of the orifice in both nozzles. During the development of the new nozzles, a CFD code for predicting the spray shape are also developed. By comparing the calculated results to the experiments, it was shown that the CFD code can predict the spray angle with reasonable accuracy. The spray angle was found to be strongly dependent on the air void geometry formed inside the orifice.